Oxirane compounds such as epichlorohydrin, cyclohexene oxide, glycidol, glycidyl ethers, and the like, usually in combination with other compounds such as alkoxynitriles, amines, amides, alcohols, and esters, are commonly used to stabilize chlorinated solvents, such as perchloroethylene, against metal induced decomposition.
Of the oxirane compounds, epichlorohydrin is perhaps most commonly used due to its proven effectiveness and ready availability. However, since epichlorohydrin has been shown by the Ames Test to exhibit mutagenic activity, its continued permissible use in chlorinated solvent stabilization systems is questionable for reasons of health and safety.
Cyclohexene oxide has been demonstrated to be an acceptable non-mutagenic substitute for epichlorohydrin in chlorinated solvent stabilization systems; however, cyclohexene oxide suffers from the disadvantage that it, itself, is unstable and develops acidity upon storage, especially when exposed to air.
It is believed that cyclohexene oxide autoperoxidizes to form a decomposition product which is believed to be cyclopentane carboxylic acid, which decomposition product causes severe pitting and corrosion of metals, particularly aluminum. Consequently, before cyclohexene oxide can be effectively used to stabilize chlorinated solvents against metal induced decomposition, the cyclohexene oxide itself must be stabilized against peroxidative decomposition.
Cyclohexene oxide is usually stabilized against decomposition by the inclusion of a stabilizing amount of butylated hydroxytoluene (BHT). However, it has been found that BHT stabilized cyclohexene oxide is not very effective in stabilizing unsaturated chlorinated solvents, for example, perchloroethylene, against metal, particularly aluminum, induced decomposition, especially when the solvent is used in degreasing operations.
It is desirable, therefore, to devise means of stabilizing cyclohexene oxide against decomposition, which stabilized cyclohexene oxide would be particularly effective in stabilizing unsaturated chlorinated solvents against metal induced decomposition in addition to having the capacity to neutralize any hydrochloric acid decomposition product.